config/media/pipewire.md: document use of wireplumber

[ahesford]

When we actually remove pipewire-media-session and don't override context.exec in the default pipewire.conf, the configuration part will need to be rewritten.

[Vaelatern]

Could we maybe also have a brief description of "Why"? I don't know why these things matter and I'm curious.

[ahesford]

@Vaelatern I've added a new introductory sentence to this section. Does that provide sufficient context?

[Vaelatern]

Yes, thank you, that helps!

[oreo639]

Also, I don't think there is a way to guarantee that the wireplumber.desktop script runs after pipewire. (correct me if I am wrong)

The previous PR changed the pipewire docs to reccomend using /etc/pipewire/pipewire.conf.d/ and ~/.config/pipewire/pipewire.conf.d/ rather than changing the /etc/pipewire/pipewire.conf:
#702

(Also, there is /usr/share/pipewire/pipewire.conf.d/ which could be used by packages if necessary.)
https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Config-PipeWire

Although keep in mind:

Note!! Properties will override the previous ones, array entries will be appended. It is not possible yet to change
or remove existing array entries. This only applied to the first level objects, arrays in properties will be overwritten as usual.

[paper42]

I really don't like recommending a solution like this, people will be confused and go to ask in #voidlinux a lot. We should at least say suggest people to prefer using their wm's startup scripts over xinitrc if this is an issue.

[ahesford]

How about I strike the "when launching from .xinitrc" paragraph (to avoid endorsing that as a solution) and change the note to

In its default configuration, wireplumber requires an active D-Bus session. When using Desktop Application Autostart symlinks, it should be sufficient to wrap the launch of a window manager or desktop environment in dbus-run-session. Users of window managers that do not respect the autostart mechanism should consult upstream documentation regarding the process for automatically starting programs at launch.

At some point, we have to be willing to tell people that this isn't Ubuntu and they might need to do some learning on their own.

[ahesford]

We should not ship configs that enable wireplumber by default when the default is to not do that. It will eventually land us in the same mess we are now trying to resolve.

I'm currently using two /etc/pipewire/pipewire.conf.d snippets to launch pipewire-pulse and wireplumber in context.exec and the concatenation works fine. We can't recommend this solution until we drop the pipewire-media-session from our default configs because launching two session managers leads to failure. Until then, it doesn't make sense to tell people to copy the system config and edit that, just so they can later add configuration snippets alongside the overridden config.

[cinerea0]

If/when use of pipewire.conf.d directories is documented in the handbook, would it make sense for it to say the order in which the configs are sourced?

[ahesford]

If/when use of pipewire.conf.d directories is documented in the handbook, would it make sense for it to say the order in which the configs are sourced?

No. That information is already described in pipewire.conf(5) so there is no need to reproduce it here.

[ahesford]

I rewrote some things to prefer custom configuration edits that will make pipewire launch wireplumber. It also notes the wireplumber.desktop file and the ordering issues surrounding its use, but should give people enough hints to find their way around alternatives if they don't want to make the config change.

[paper42]

I think this sounds better?

Suggested change

	package was originally provided and, in Void, configured to run by default to
	package was originally provided and, in Void and configured to run by default to

[ahesford]

I reworded to

Suggested change

	package was originally provided and, in Void, configured to run by default to
	package was originally provided in the Void `pipewire` package and configured to run by default to